Variable convergent-divergent jet propulsion nozzle

ABSTRACT

A variable convergent-divergent jet propulsion nozzle includes a jet pipe conducting gas under pressure, a ring reciprocable by power axially of the exterior of the jet pipe, a ring of flaps defining a converging nozzle section pivoted on the reciprocable ring, and a ring of flaps defining the diverging downstream portion of the nozzle pivoted to the convergent flaps near the downstream end of the convergent flaps. When the flaps are moved rearwardly by power, a cam and roller type girdle closes in the divergent portion of the nozzle, and with it the convergent portion. A ring of fairing flaps each fixed onto the exterior of one of the divergent flaps creates a boattail fairing. These cooperate with tracks which guide the assembly of boattail and divergent flaps as it is projected or retracted.

United States Patent 1 Smale et al.

VARIABLE CONVERGENT- DIVERGENT JET PROPULSION NOZZLE Inventors: CharlesH. Smale; Esten W. Spears,

Jr., both of Indianapolis, Ind.

Assignee: General Motors Detroit, Mich.

Filed: Oct. 1, 1971 Appl. No.: 185,525

Corporation,

References Cited UNITED STATES PATENTS Benedict... .....239/265.39 X

Mehr....; ..239/265.39 X Motycka ..239/265.39

Jan. 23, 1973 [57] ABSTRACT A variable convergent-divergent jetpropulsion nozzle includes a jet pipe conducting gas under pressure, aring reciprocable by power axially of the exterior of the jet pipe, aring of flaps defining a converging nozzle section pivoted on thereciprocable ring, and a ring of flaps defining the diverging downstreamportion of the nozzle pivoted to the convergent flaps near thedownstream end of the convergent flaps. When the flaps are movedrearwardly by power, a cam and roller type girdle closes in thedivergent portion of the nozzle, and with it the convergent portion. Aring of fairing flaps each fixed onto the exterior of one of thedivergent flaps creates a boattail fairing. These cooperate with trackswhich guide the assembly of boattail and divergent flaps as it isprojected or retracted.

4 Claims, 6 Drawing Figures VARIABLE CONVERGENT-DIVERGENT JET PROPULSIONNOZZLE Our invention relates to jet propulsion nozzles such as are usedwith turbojet and other engines for high speed propulsion of aircraft.It is particularly directed to improvements in nozzles of the variableconvergentdivergent type which, as is well known, are employed with jetengines for aircraft which have a wide speed range, particularly thosein which an afterburner is provided so that a substantial variation injet nozzle area is required between dry and afterburning operation. Oneexample of such a propulsion nozzle is disclosed in Spears et al. U.S.Pat. No. 3,004,385, Oct. 17, 196].

The principal object of our invention is to provide aconvergent-divergent jet propulsion nozzle better adapted to therequirements of practice than those commonly used. Other objects of ourinvention include the provision of such a nozzle of lighter weight thanthose commonly employed, one which is infinitely variable in area, onewhich has a low angle of divergence of the divergent portion of thenozzle in all ,degrees of opening, one which has a low parasitic drag,one which has minimum cooling requirements because of the relation ofthe movable nozzle flaps to the jet pipe on which they are mounted, andone which is simple in structure and well adapted to stand the hightemperature flow of gas at high pressure encountered in such nozzles.

The nature of our invention and its advantages will be apparent to thoseskilled in the art from the succeeding detailed description of thepreferred embodiment and the accompanying drawings.

FIG. 1 is a sectional view, taken in a plane containing the axis ofsymmetry thereof, of an annular variable area jet nozzle.

FIG. 2 is a similar view, taken in a plane angularly displaced from theplane of FIG. 1.

FIG. 3 is a fragmentary plan view illustrating the nozzle closing camarrangement.

- FIG. 4 is a cross sectional view of the same taken in the planeindicated by the line 44 in FIG. 1.

FIG. 5 is a fragmentary sectional view taken in the plane indicated bythe line 5-5 in FIG. 2.

FIG.'6 is a fragmentary sectional view taken in the plane indicated bythe line 66 in FIG. 2.

- Referring first to FIGS. 1 and 2, the preferred installation of ourinvention includes a jet pipe or exhaust pipe 2 which is a slightlyconverging duct carrying the combustion products from a gas turbineengine. The diameter of the jet pipe is about eight-tenths of the lengthof the jet pipe and nozzle structure illustrated.

The jet pipe is double-walled, having an outer wall 3, which is aprimary structural strength and pressurecontaining wall of circularcross section, and an inner wall or liner 4 separated from the wall 3 bya cooling air space. The liner bounds a space in which an afterburner(not illustrated) is mounted for reheating the combustion products asand when desired. The jet pipe terminates in anoutlet at 6 fromwhich thepropulsive jet is discharged into the nozzle structure of our invention.The upstream end of the outer wall 3 is bolted to the downstream end ofan engine exhaust pipe 7 into which inner wall 4 extends.

A nozzle support ring 8 of heavy sheet metal is bolted at its forwardedge to a flange 10 extending outwardly from the forward end of wall 3.The upstream end of ring 8 bears an outwardly extending flange II towhich is removably secured a slightly tapering fairing 12 of circularcross section, this defining the outer boundary of the nozzle assembly.Flanged cutouts 14 in the nozzle support ring reduce its weight andprovide for flow of cooling air into the interior of the ring. Suchcooling air may enter from any suitable source through holes such as13in flange 11.

Variation of the configuration of the nozzle is effected by an operatingring 15, guided for movement axially of the jet pipe by six pairs ofrollers 16 rotatably mounted on posts 17 fixed to the ring 15 (see alsoFIG. 6). Each pair of rollers traverses a channel section track 19integral with brackets 20 by which it is bolted to the support ring 8.This mounting tolerates radial expansion of the parts and provides forfree movement of the operating ring 15 axially of the jet pipe. Asshown, ring 15 is in its forward limit of travel; that is, for wide opennozzle.

The operating ring is moved by six equi-spaced operating cylinders oractuators 22 coupled to the ring and coupled to brackets 23 extendingfrom flange 10. Any suitable means for operating and synchronizing theseactuators, as well known in the art, may be employed so that the ring 15is moved by the six actuators while remaining perpendicular to the jetpipe axis.

The converging part of the jet nozzle is defined by a ring of eighteenflaps 24 which overlap at their lateral margins, as is well understood,and which are swingable about hinge pins 26 mounted in brackets 27extending from the rear edge of operating ring 15. Each flap 24 includesa box section stiffening rib 28 (see also FIG. 5) which is integral witha hinge element 30 supporting a pin 31 which couples the convergentflaps 24 to the divergent flaps outward and downstream of them.

There is a ring of eighteen divergent flaps 32 (see also FIG. 4) withthe margins overlapping as indicated at 34 and overlapping farther asthe nozzle is closed. Each divergent flap 32 is borne by an axiallyextending box section support 35, these being aligned with the ribs 28on the converging flaps and defining a clevis for the hinge pins 31.Thus, each divergent flap is hinged to a convergent flap by pin 31adjacent to the downstream end of the convergent flap and slightlyupstream of the beginning of the effective portion of the convergentflap. It will be noticed, as shown in FIGS. 1 and 2, that there is aslight axial overlap and a slight radial gap between the two sets offlaps, as indicated at 36. Thus, the gas flowing from the convergentflaps is directed to the-interior of the divergent flaps and, by ejectoraction, some air which is cooler than the propulsive gases is drawnthrough the gap at 36 and serves to film cool the divergent flaps tosome extent.

Each support 35 includes two upstanding pairs of brackets 38 definingparts of aligned hinge joints which couple the divergent flaps 32 tocams 39 forming parts of a drawstring nozzle closing device to bedescribed. As shown clearly in FIG. 3, the bracket 38 at each of theadjacent cams 39 bears two knuckles which are coupled by a hinge pin 40to the cams 39. Each cam 39 defines two cam tracks 42 on opposite facesof the cam, these cam tracks of adjacent cams diverging in the directiontoward the upstream end of the jet pipe, as shown in FIG. 3.-The camtracks are occupied, by rollers 43 mounted, as shown in FIGS. 3 and 4,on a roller carrier 44 (see also FIG. 1) which is threaded onto the endofa strut 46 and secured by ajam nut 47. There are eighteen such rollercarriers and struts, and each strut is fixed by a swing joint at 48 tothe nozzle support ring 8. Thus, the roller carriers 44 may swingradially in and out but are restrained against movement axially of thejet pipe.

As a result of this, when the actuators 22 move the operating ringrearwardly of the tailpipe, the ring of convergent flaps 24 is carriedrearwardly by hinge pins 26 and these carry with them the ring ofdivergent flaps 32 through pins 31. As the divergent flaps moverearwardly, the cam tracks 42 traveling past the rollers 43 pull thedivergent nozzle flaps progressively into a smaller radius as therearward movement proceeds. Through the hinge connection 31 between thetwo sets of flaps, the convergent flaps are forced inwardly along withthe divergent flaps, and the nature of the movement will be apparentfrom the broken lines in FIG. 1 which show the final closed position ofthe nozzle as compared to the open position in solid lines. Closing isresisted by pressure within the nozzle, which pressure acts to open thenozzle when operating ring 15 is moved forwardly.

The nozzle assembly also includes a ring of eighteen boattail fairingflaps 50 of sheet metal, each of which is fixed to a support 35. Asillustrated in FIG. 2, the hinge joint brackets 38 include flanges S1 towhich the boattail fairing flaps 50 are fixed by suitable fasteners sothey are rigid with supports 35 and flaps 32. The upstream ends of theboattail fairing flaps are slidably received within the downstream endof the annular fairing 12 and are guided by two followers 52 at theforward end of each boattail fairing flap. Each follower is guided by atrack 54 fixed to the exterior of the nozzle support ring 8 (thirty-sixtracks in all).

The gap between tailpipe 2 and operating ring 15 is closed againstescape of exhaust gas by two annular seals mounted on ring 15. Seal 56cooperates with the upstream ends of flaps 24 at the hinge joint, andseal 58 slides over outer wall 3 as ring 15 is shifted.

We have described a nozzle having eighteen flaps in each ring andcorresponding numbers of other parts. Obviously, these figures may bechanged if desired.

As will be seen upon consideration of the description of the preferredembodiment of our invention, it provides a structure very well adaptedto satisfy the objects outlined in the beginning of this description.Particularly, it will be noted that there is a small angle ofconvergence of the boattail, a very low boattail drag, a very smalldivergence angle of the divergent flaps, a simple mechanical linkage,and an arrangement in which the convergent flaps are largely shieldedfrom the hot gas when the nozzle is open and temperatures are highbecause of afterburning operation.

The detailed description of the preferred embodiment of the inventionfor the purpose of explaining the principles thereof is not to beconsidered as limiting or restricting the invention, since manymodifications may be made by the exercise of skill in the art.

We claim:

1. A variable convergent-divergent jet propulsion nozzle comprising, incombination, a jet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a retracted position in which the downstream ends of the flapsare approximately coterminous with the jet pipe and a projected positionin which the flaps extend principally beyond the jet pipe outlet; anouter ring of flaps surrounding the inner ring and extending downstreamfrom the inner ring, the outer ring flaps having their upstream endsguided for reciprocation axially of the jet pipe and being hinged to theinner ring flaps near the downstream end of the inner flaps; and alinkage interconnecting the outer ring flaps effective to reduce thediameter of the outer flap ring and thereby the diameter of the innerflap ring upon translation of the operating ring and flaps rearwardly ofthe jet pipe; the inner ring flaps defining a convergent nozzle sectionand the outer ring flaps defining a divergent nozzle section.

2. A variable convergent-divergent jet propulsion nozzle comprising, incombination, a jet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a retracted position in which the downstream ends of the flapsare approximately coterminous with the jet pipe and a projected positionin which the flaps extend principally beyond the jet pipe outlet; anouter ring of flaps surrounding the inner ring and extending downstreamfrom the inner ring, the outer ring flaps having their upstream endsguided for reciprocation axially of the jet pipe and being hinged to theinner ring flaps near the downstream end of the inner flaps; and alinkage interconnecting the outer ring flaps effective to reduce thediameter of the outer flap ring and thereby the diameter of the innerflap ring upon translation of the operating ring and flaps rearwardly ofthe jet pipe; the inner ring flaps defining a convergent nozzle sectionand the outer ring flaps defining a divergent nozzle section and aboattail fairing.

3. A variable convergent-divergent jet propulsion nozzle comprising, incombination, ajet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a forward position in which the flaps are largely retracted overthe jet pipe and a rearward position in which they are largely projectedbeyond the jet pipe outlet; fixed to an outer ring flap and extendingforwardly exteriorly of the operating ring; and means fixed to the jetpipe guiding the forward ends of the fairing flaps for reciprocationaxially of the nozzle and thereby further locating the outer ring flaps.

4. A variable convergent-divergent jet propulsion nozzle comprising, incombination, ajet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a forward position in which the flaps are largely retracted overthe jet pipe and a rearward position in which they are largely projectedbeyond the jet pipe outlet; an outer ring of flaps surrounding the innerring and extending downstream from the inner ring, the outer ring flapshaving their upstream ends guided for reciprocation axially of the jetpipe and being hinged to the inner ring flaps near the downstream end ofthe inner flaps; and a linkage interconnecting the outer ring flaps nearthe downstream end of the inner flaps; a linkage interconnecting theouter ring flaps effective to reduce the diameter of the outer flap ringand thereby the diameter of the inner flap ring upon translation of theoperating ring and flaps rearwardly of the jet pipe; the inner ringflaps defining a convergent nozzle section and the outer ring flapsdefining a divergent nozzle section and a boattail fairing.

3 3 UNITED STA'lES PATENT OFFICE CERTIFIQATE 0F PatentNo 3,712,547 DatedJanuary 23, 1973 Inventor(s) Charles- H. smells and Esten W. Spears, Jr.

It is certified that error appears in the shore-identified patent andthat said Letters Patent are hereby corrected as shown below:

Colum 4, lines 49 through 53, delete "fixed to an .1

outer ring flap and extending forwardly exteriorly of the operatingring; and means fixed to the jet pipe guiding the forwardends of. thefairing flaps for reciprocation axially of the nozzle and then'ebyfurther locating the outer ring flaps."

and "insert the following an outer ring of flaps surrounding the innerring and projecting downstream from the inner ring, the outer ring flapsbeing hinged to the inner ring flaps nearpthe downstream end of theinner flaps; a linkage interconnecting the outer ring flaps effective toreduce the diameter of the outer flap ring and" thereby the diameter ofthe inner flap ring upon translation of the operating ring and flapsrearwardly of the jet pipe; the inner ring flaps defining a convergentnozzle section and theouter ring flaps defining a divergent nozzlesection and a'boattail fairing.

Column 5', line 7 through column 6, line '8, delete "an outer ringoflflaps surrounding the inner ring and projecting downstream fromtheinner ring, the outer ring flaps being hinged to the inner ring flapsnear the downstream end of the inner flaps; a linkage interconnectingthe outer ring flaps effective to reduce the diameter. of the outer flapring and thereby the diameter of" the inner flap ring upon translationof the operating ring and 'flaps re'arwardly of the jet pipe: the innerring flaps defining a convergent nozzle section and the outer ring flapsdefining a divergent nozzle section and a boattail v fairing." I p I a i"and insert the following fixed to an outer ring flap and extendingforwardly exteriorly of the operating ring; and means fixed to the jetpipe guiding the forward ends of the fairing flaps for reciprocationaxially of the nozzle and thereby further locating the outer ring flaps.J

Signed and sealed this 27th day of Novemher 1973.

(S A l Attest: V

EDWARD M.FLETCHER, JR. RENE D. TEGTMEYER Attesting Officer"; ActingCommissioner of Patents

1. A variable convergent-divergent jet propulsion nozzle comprising, incombination, a jet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a retracted position in which the downstream ends of the flapsare approximately coterminous with the jet pipe and a projected positionin which the flaps extend principally beyond the jet pipe outlet; anouter ring of flaps surrounding the inner ring and extending downstreamfrom the inner ring, the outer ring flaps having their upstReam endsguided for reciprocation axially of the jet pipe and being hinged to theinner ring flaps near the downstream end of the inner flaps; and alinkage interconnecting the outer ring flaps effective to reduce thediameter of the outer flap ring and thereby the diameter of the innerflap ring upon translation of the operating ring and flaps rearwardly ofthe jet pipe; the inner ring flaps defining a convergent nozzle sectionand the outer ring flaps defining a divergent nozzle section.
 2. Avariable convergent-divergent jet propulsion nozzle comprising, incombination, a jet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a retracted position in which the downstream ends of the flapsare approximately coterminous with the jet pipe and a projected positionin which the flaps extend principally beyond the jet pipe outlet; anouter ring of flaps surrounding the inner ring and extending downstreamfrom the inner ring, the outer ring flaps having their upstream endsguided for reciprocation axially of the jet pipe and being hinged to theinner ring flaps near the downstream end of the inner flaps; and alinkage interconnecting the outer ring flaps effective to reduce thediameter of the outer flap ring and thereby the diameter of the innerflap ring upon translation of the operating ring and flaps rearwardly ofthe jet pipe; the inner ring flaps defining a convergent nozzle sectionand the outer ring flaps defining a divergent nozzle section and aboattail fairing.
 3. A variable convergent-divergent jet propulsionnozzle comprising, in combination, a jet pipe terminating in an outlet,an operating ring translatable axially of the exterior of the jet pipe,an inner ring of flaps hinged at their forward ends to the operatingring, the said flaps having a forward position in which the flaps arelargely retracted over the jet pipe and a rearward position in whichthey are largely projected beyond the jet pipe outlet; an outer ring offlaps surrounding the inner ring and projecting downstream from theinner ring, the outer ring flaps being hinged to the inner ring flapsnear the downstream end of the inner flaps; a linkage interconnectingthe outer ring flaps effective to reduce the diameter of the outer flapring and thereby the diameter of the inner flap ring upon translation ofthe operating ring and flaps rearwardly of the jet pipe; the inner ringflaps defining a convergent nozzle section and the outer ring flapsdefining a divergent nozzle section and a boattail fairing.
 4. Avariable convergent-divergent jet propulsion nozzle comprising, incombination, a jet pipe terminating in an outlet, an operating ringtranslatable axially of the exterior of the jet pipe, an inner ring offlaps hinged at their forward ends to the operating ring, the said flapshaving a forward position in which the flaps are largely retracted overthe jet pipe and a rearward position in which they are largely projectedbeyond the jet pipe outlet; an outer ring of flaps surrounding the innerring and extending downstream from the inner ring, the outer ring flapshaving their upstream ends guided for reciprocation axially of the jetpipe and being hinged to the inner ring flaps near the downstream end ofthe inner flaps; and a linkage interconnecting the outer ring flapseffective to reduce the diameter of the outer flap ring and thereby thediameter of the inner flap ring upon translation of the operating ringand flaps rearwardly of the jet pipe; the inner ring flaps defining aconvergent nozzle section and the outer ring flaps defining a divergentnozzle section; a ring of boattail fairing flaps each fixed to an outerring flap and extending forwardly exteriorly of the operating ring; andmeans fixed to the jet pipe guiding the forward ends of the fairingflaps for reciprocation axially of the nozzle and thereby furtherlocating the outer rinG flaps.